Compression pump



Nov. 20', 1923 mmmg v E. D. DUNNING COMPRESSION PUMP Origin? g iledApril 29, 19%? Patented Nov. 20, 1923.

UNITED STATES crates.

" ELMER D. DUNNING, OF PHILADELPHIA, PENNSYLVANIA.

oomranssron rurrr.

Application filed April 29, 1919, Serial No. 293,387. Renewed September27,. 1923.

To all whom it may concern:

Be it known that I, E-LMER D. DUNNING, a citizen of the United States,and resident of Philadelphia, in the county of Phila- 6 delphia andState of Pennsylvania, have invented certain new and useful Improvements in Compression Pumps, of which the following is a specification. IMy present invention relates to compres- 10 sion pumps of the typecommonly employed as tire pumps and particularly tothe sma ler and morecompact types adapted to be installed on the frame of an automobileengine. Such pumps are required to deliver '15 compressed airatpressures up to say 60 pounds for the smaller tires and to operate withdecreasing volume of output and decreasing1 efficiency at the higherpressures require for larger tires up to say 90 to 120 pounds.

For such purposes it is common to employ a double pump comprising twopiston heads rigidly connected base to base and reciprocated inoppositely aligned cylinders by a special form of scotch yoke driverconsisting of an eccentric fitted between the adjacent bases of thepiston heads and acting alternately on one and then on the other toforce the compression strokes of each the suction strokes beingaccomplished by traction through the rigid connection between the heads.

My present invention consists in certain important improvements in pumpsof this type.

For instance, such pumps for such purposes so far as I am aware havethe. ratio of piston area to stroke, usuall about 3 to 1, that isto-say, 3 square inc es of piston areafor one inch stroke, or 2 squareinches for a 5} inch stroke. This gives a transverse strain on the driveshaft of say 300 pounds when pumping against 100 pounds back. pressurewhich is quite as high t as is safe for such devices as ordinarilyconstructed. Nevertheless, I have discovered that for the particularnumerical values here involved, many advantages can be gained bydoubling the piston area without increasin the stroke, for instance, ifthe stroke be kept i inch and the piston diameter increased to '23-inches the area will be about 41} inches which gives a ration ofpis tonarea to-stroke of about 6 to 1 instead of 2 or 3 to l. I thereb doublethe volume of the pump space whi the circumference inch nor more than 1inch with the clear- .ble leakage besides practically doubling the caacity of the pump.

t is true the doubling of the piston area will bring the'transversestrain on the drive shaft up to 450 pounds when pumping at pounds persquare inch, but this is taken care of by an improved bearing and proportioning' for the drive shaft while the increased diameter of the pumheads gives added space for a much wi er and more centrally locateddriver, without encroaching on the space necessary for structuralstrength of the rigid member connecting the two piston heads. I

While certain variations are possible in these dimensions withoutdeparting from the spirit of this part of my invention, li prefer isthat the ratio of piston area to stroke be not less than 5 to 1 nor morethan 8 to l and that the stroke be not less than a of an Eli anoe at theend of the stroke not more than. one-sixth the stroke nor less than 3 ginch. The rotary crank element is preferably formed as an eccentriccircle of relatively large diameter, said diameter being approx imatelytwice the stroke or four times the h radial distance between the tcentric head and the axis of ti" drive This radius will be *3 inch forinch and as the load acts at right angles c radius only mid-stroke, whenthe pressure in the compression space is not about 15 pounds per squareinch, its t load on the crank shaft even for 4;; l,

iston area, is not over 100 pounds plus rictional resistance which issmall because of the peculiar design employed.

Many other features of my invention. late to structural improvements andmost '5 them may be embodied in pumps of ent proportions, and some ofthem in pumps which have only a single piston hear pump chamber. Theseimprovements clude the following:

in the double headed piston the two heads are connected by a solidlongitudinaber unweakened by slotting for d shaft and guided andprevented from tion by contact with and face r rotary crank element.'llhe friction ear of this sliding contact may be reduced bellowing. outthe end thrust surface of rotor so as to leave an annulus oil at width,and the hollow may be extended deep enough to materially decrease theeccentric weight, provided the walls are kept thick a enough to have thenecessary strength. The

and the outlet passages communicate with a straight outlet passagedrilled in the wall of the cylinder from end to end therof.

The length of the shaft bearing is more than four times crank radius and1s removably but rigidly secured by a cylindrical exterior bearingsurface accurately machined to fit an opening formed therefor in theside of the cylinder casing and by an annular face fitting against themouth thereof at right angles to the cylindrical bearing surface. Theopening in which the c lindrical bearing fits is preferably of s ightlygreater diameter than the eccentric driving head so that the bearing,drive shaftand head may be radially inserted in or removed from thecylinder by simply removing the screws which hold the annular flange inplace.

Means for throwing the drive shaft into and out of driving engagementwith asuitable source of power as for instance the cam shaft of anautomobile engine, is provided in the form of a clutch collar splined tothe drive shaft and movable endwise thereon b a swivel fork pinned to anendwise movaiile shaft slidably supported parallel with the drive shaftand adapted to be non-positively locked in the operative or inoperativeosition of the clutch by a spring pressed all arranged to laterally engasuitably spaced notches in said movable s aft.

The above and other features of my invention may be more fullyunderstood from the following description of a desirable embodimentthereof in connection with the accompanying drawings, in which- Figure 1is a horizontal section on the axis of the device, and

Figure 2 is a vertical section at right angles to the axis.

As shown in these drawings. the body of the pump comprises a cylindricalcasting 1 having a straight cylindrical bore and formed exteriorly withradiating flanges 3, suitable standards or supports 4, formed with boltholes 5 for securing the same. a longitudinal rib 6 having a straightoutlet passage 7 drilled therethrough and a transverse outlet passage 8;also a lateral opening 9 having straight walls 10 and a fiat face 11.The opening is of size sufficient to permit crank shaft and rotor to beinserted or withdrawn, the said opening being normally closed by thecrank shaft bearing when the latter is in position.

Fitting the cylinder bore 2 is a double faced piston comprisingoppositely facing piston heads 13. which may be provided with elasticsteel rings '14 of t 1e typecommonly employed for pistons of automobilemotors. Said piston heads are rigidly connected and preferably castintegral with a longitudinal member 15 having a strengthenin rib l6 anda fiat face 17 extending para lel with the axis of the cylinder.At'r-ight angles to the ends of said face, are parallel bearing surfaces18, said surfaces 18 and 17 being of shape and dimensions adaptedto fitthe rotary driving member on two sides and the end thereof,respectively.

The cylinder is closed by similar heads 20 each comprising a circularcasting having air inlet and outlet passages drilled therein, preferablyall in the same straight line. These passages are preferably formed bydrilling a through hole of the size of the central part of the passage22, reaming enlargements 23 from each end to form shoulders 24, a thenscrew-threading for screw-plug 25 and sleeve 26. The inner end of thescrew sleeve 26 is formed with a valve seat 27 for inlet valve 28normally held in the closed position by spring 29. resting on shoulder24. The other shoulder 24 forms a valve seat for outlet valve 31normally held closed by spring 32 abutting against screwplug 33. Thepassage 22 has a central open ing 34 ommunicating with the pump chamber.preferably at the center thereof.

The outlet passages have lateral openings 35 registering with the outletpassage 7 formed in the wall of the cylinder. The cylinder heads areheld in place by suitable screws or bolts not shown.

The removable bearing member fits into and closes the opening 10 and hasa projecting portion 42 su portin the drive shaft 43 up to a point eosely a jacent the rotor 44, and of reduced diameter toward the end soas not to interfere with rearward movements of the piston heads. It alsohas a rear extension 45 which makes the total length of the bearing verygreat as compared with the crank radius. lit also has an extended bearin46 contacting firmly with the interior of walls 10 and an annular flange47 adapted to be secured by screws 48.

As a means for connecting-the drive shaft and source of power, I providea clutch collar 50 having longitudinal projecting lugs 51 slidablysecured on the drive shaft by a semi-circular spline 52 engaging slot53.

The clutch collar has a swivel groove 54 ltl) inverse around which fitsfork 55 secured to shaft 56 by taper pin 57. The shaft 56 is slidablsupported in a lug 58 on the cylinder, pre erably integral therewith andin a In 59 preferably integral with the drive s aft bearing, adapted tosupport shaft 56 close up to the plane of the clutch collar.

The shaft 56 may be supplied with operating handle 60 for shifting itendwise and may be non-positively secured in the operative orinoperative position by pressure of spring 61 on ball 62 located indrill hole 63 and engaging notches 64 on the under side of shaft 56.

structurally the device is extremely simple and composed of extreme-1few parts very unlikely to get out of or er and very easy to replace orrepair, the essentials exelusive of fittings, consisting of a singlepiece cylinder, a single piece piston, a single piece drive shaft andeccentric and single piece bearing, and two single piece cylinder heads.The fittings also are simple and few in number comprising; only the fourvalve plugs, balls and springs, the four piston rings and 16 screws, 6for each head and l for the hearing. The clutch device is equally simplecomprising only spline, collar, fork, shaft, pin, ball and spring.

The pump is well adapted for operation at 6 to 8 hundred revolutions perminute and can be driven up to a thousand or fifteen hundred revolutionsfor short periods.

Hence, it is peculiarly adapted for driving from any exposed rotatingshaft or other part of the motor or transmission by either positive orfrictional connection which be either a clutch or a gear.

I claim:

1. In a double pump, a single straight bore tube forming opposedcylinders, a one piece web connected, double faced piston, single piececombined eccentric and drive shaft, a suitable bearing support for titshaft, and one piece detachable c lind heads with inlet and outletvalves coated therein.

2. In a pump, a one iece cylinder, an out-- let passage through t ecylinder wall and extending in the direction of the length of thecylinder, a one piece detachable c tinder head closing one end of thecylin er, an opening Or passage extending through said cylinder head,and connecting the cylinder with the outlet passage.

3. In a pump, a one piece cylinder, an opening or passage through thecylinder wall and extending in the direction of the length of thecylinder, one piece detachable cylinder heads closing the ends of thecylin dcr, an opening or passage extending through said cylinder headsand opening into the outlet passage and the cylinder, and valves placedin the cylinder head passage (t1o form inlet and outlet valves for thecylin- Signed at New Yorlr city, in the county f New York and State ofNew York, this 21th day of April, A. D. 1919.

ELMER D. fDUllNlll lG.

